Internal combustion engine



FIG. 1 is a left/front perspective view of an internal combustion engine showing my new design.

FIG. 2 is a front view thereof.

FIG. 3 is a rear view thereof.

FIG. 4 is a right side view thereof.

FIG. 5 is a left side view thereof.

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken line showing of unclaimed portions of the internal combustion engine forms no part of the claimed design. 

The ornamental design for an internal combustion engine, as shown and described. 